Auxiliary driving light



July 4, 1933. J KOUBEK 1,916,514

AUXILIARY v DRIVING LIGHT Filed May 9, 1931 3 Sheets-Sheet 1 gnuewhn VF mm a %1 W" a a i .464. 9

l Cltfozmwo July 4, 1933. J. L. KOUBEK 1,916,514

IIIIIIIIIIIIIIIIIII HT A (A I Filed May 9, 1931 3 Sheets-Sheet 3 Patented Jul v 4, 1 933 -,,;.UN1 DI T TES PATENT "OFFICE JOHNZ'L. ,KOUBEK, or ANDERSON,-iNnIAnm-AssmNon 'ro GUIDE-LAMP conrom'rron',

OF mnnnson, INDIANA, A CORPORATION on DEL WARE I AUXILIARY DRIVING LIGHT Application filed Ma a,- 1931. S'eri al'No. 536 ,177

, This invention has to. doparticularly with a lamp designed to throw light to the far sides of an automobile to light the way in turning corners and to give better illumination in 5 case of fog. fTllG lamp is intended for use in conjunction with the headlamps regularly used on automobiles. Go-riventionalfheacb lamps project most of their light downthe road, withasmaller proportion directedv to the sides of theroad and to the foreground for general illumination. As a consequence,

when the car is turned, an insutflcient quantityv of light'or none at all projectedin the direction in which the turn is being made.

My improved .lamp is preferably" so, designed that while itsbeams slightly overlap the beams from the ieadlamps, the greater proportion of the light is directed to the extreme sides of the roadway to which the head lamp rays are not directed. The light from my lamp not only permits turns to be'made with convenience and safety but by'turning off themain headlamps, and turning onim'yimproved auxiliary lamp, very good fog lighting is obtained. 'lhegsidewise directed beams from my lamp illuminate the .way much better in fog than do the forwardly directed headlamp beams for less of the light is reflected from the suspended particles of i Water-vapor into the eyes of the driver."

My improved lamp is cl'iaracterizedby absence of moving parts and consist-sin it'spreferred form of a simple parabolic reflector, an incandescent lamp with a filament at the focus of the, reflector, and lens of special design for directing the light into two laterally spaced beams with a dark between them, this space being normally filled in with light from the headlamps. As the auxiliary light 40 mg will be most useful in turning corners I' have preferably arranged my lamp in a special lighting circuit containing a switch operated by turning the steering gear of the 7 car so that when the front wheels of-the car have been turned through a predetermined angle the auxiliary lamp is turned onto project its beams attheextreme sides of the road affording illumination for either direction of.

turn. 7 The lens'may be of any one of a number of with verticalprisms on one face and super- ,imposedvertical concave flutes on the other face. By varying the angle of the prisms, the radius of the flutes and the thickness of .ing my invention.

designs, arid general is characterized by the provision of a combination of vertical flutes and vertical prisms for giving the desired lateral spread to the. light. In some forms of -myinventionthe prisms and flutes are formed on opposite sides of the lens; while in other forms they are combined ononc face of the lens, leaving the outer face a plain surface which maybe readily cleaned.

I The preferred design of lens is provided the glass, the divergence" of the beams -.=and to" their lateral spreadmay be very readily controlled. ,If desired the lensmaybeprovided With horizontal prisms to vary the depthflf 1 the beam.

-I live parti s ularly emphwized -the value of my lamp for use as an auxiliary lamp on automobiles. v Howevcr, fundamentally; the design produces two long, narrow and more or less widely separatedbeams. Lighting appa} ratus having thesecharacteristics is likewise l6 useful for roadway illumination, for aeroplane landing field beacons, andkindred service, and it is to be understood that all such uses come 'Within the scope of my invention,

hether'thelamp be arranged so that beams are projected in 'a horizontal plane or in avertical plane, or anyjother. v

Inthe drawings v y 7 Figure 1 isa front view of a lamp embodyvvFigure 2 1s a vertical'section, showing by light rays, andin an'exaggeratedmanner, the

and atan angle B of about degrees. as

automobiles.

;loss increases.

Figure 6 is a horizontal section corresponding to Figure 3 but showing the bulb equipped with a cap. 7

Figure 7 is a perspective view of the cap shown in Figure 6.

Figures 8 to 13 are horizontal sections through modified forms of lens.

The construction of the lamp is conven tional except for the lens although it is the combination of lens, reflector and light source that produces the desired illumination,

Referring now to the preferred construe tion shown in Figures 1 to 4, the lamp consists of a housing 10, containing a plain parabolic reflector 12, covered by my improved lens 14, held on by lens retaining ring 16. The lens ring may be secured to the housing in any suitable manner. The reflector is equipped with a bulb 24 having its filament 26 at the focus of the reflector.

v The construction of the lens is best illustratedin Figure 4, which is a horizontal section through a portion of it. On the side nearer the light source, the lens is provided with vertical prisms 28, while on the opposite side it is provided with relatively sh allow vertical flutes30, coextensive with the prisms.

Both the prisms and flutes are symmetrical with respect to planes normal to the plane of thelens and joining theapices of the prisms with the centers of curvature of the flutes.

In the design illustrated the prisms have angles, and the radius of the flutes is The minimum thickness' of the lens. is

I have found these proportions to be most advantageousfor use on auxiliary lights for i v The advantages of these proportions will be. apparent by tracing the ray which I have marked A on Figure 4. This ray strikes one of the prisms near its apex,

shown. With this angle, the loss of light byreflection at the surface of the glass is about 7 If the angle is increased the loss in creases so rapidlyas to render the design so inefficient as to be commercially impractical. In other words, this angle is so chosen that the loss of light by reflection is the maxi mum permissible from commercial considerations.

:Following the beam through the glass it strikes the surface of the flute and is deflected sharplvto the left. cidence C is about 37. With this angle, the loss of light by reflection within the glass is about 12%. As the angle is increased. this Thus 'at 39 the loss is 18%. At 41 49' the loss becomes For certain designs where the amount of light at the extreme spread of the beam is not an important factor, it might be permissible to go to 39 Beyond this the loss increases so rapidly as to render the design so ineflicient as to be impractical. Like the angle of incidenc-eat the prisms 28, this angle is so chosen The angle of in-' terially decreased the ray A will emerge from the surface of the flute nearer its axis of sym-' metry and will consequently not be deflected to the left to the full amount desired. .The conditions specified are optimum conditions.

By studyingthe other rays it will be noted that the rays are spread laterally by the action of the flutes, and that each prism and flute directs a fan shaped beam of light to the left and another fan shaped beam of light to the right.

The center is dark, except possibly for a very slight amount of light diffusedby the rays striking the'extreme tips of the prisms or the extreme depths of the troughs between them.

In commercial production of lenses by pressing, it is not possible to accurately shape:

The headlamps 39 are supplied with current from battery 40 through the ammeter and the usual operator controlled switch 42. The auxiliary lamp 10 is connected'with the battery circuit beyond the ammeterand its circuit is controlled by switch 44 of any suit- The corresponding com- 3, .POSltG beam patterns are shown on Figure 3.

of the beam have pref- K able construction connected to a part of the steering gear, for example the pitman arm. When the steering gear is turned through a predetermined angle, depending uponthe adjustment of the switch, the auxiliary, lamp 10 is turned on illuminating the farsides of the road. The auxiliary lamp is also provided with a separate connection to the battery .in any suitable manner, for example,

through the battery terminal on the dash ammeter. This connection iscontrolled by a separate switch 46 so that if desired the lamp may beused when going straight ahead through fog, the headlamps in such case being turned off, and the cowl lamps 48 being used asmarkers. V

The construction is susceptible of some modification in practice. prisms may be made slightly convex or concave, if desired to give a certain amount'of For example, the

, be varied by changing the radius of curvature form of lens.

of the flutes, but owing'to the symmetry of the design the light will be evenly distributed throughout the-beams.

The angles ofthe prisms may be varied to control the degreeof divergence of the beams. 60 is the limit for maximum divergence for a lesser angle prism results in so much loss by reflection as to be impractical.

In Figure 6, I have illustrated the lam shown in Figure 3 with the bulb provide with a fog cap 36. This cap is illustrated also in Figure 7. As indicated by the dotted line in Figure 6 the cap will cut off all direct rays issuing from the filament. The only light issuing from the lamp will then be the light striking the reflector and redirected by the lens. As shown in Figure 3 this light is projected to opposite sides of the road. With this arrangement no light of any sort is directed forwardly. It, isthe forwardly directed light that is reflected by the particles of moisture in the air in foggy weather,

making it impossible to see ahead. By elim-' inating the forwardly directed light, very good fog illumination is obtained from the sidewise directed beams. Q

In Figure 8, Ihave'illustrated a modified This form differs from the form shown in Figure 4 in that the prisms 28 are truncated, as indicated at 38 so that some of the rays will pass through the lens without appreciable change in direction. This lens will not give as satisfactory illumination under fog conditions, but will iluminate the full width of the road should this be desired. 7

The lens'shown in Figure 9 differs from the lens of Figure 4 in that I have employed convex flutes as at 40 instead of concave flutes.

As shown in Figure 10, the lens shown in Figure 9 may be modified by truncating the pris1ns,'as shown at 42.

In Figure 11, I have shown a modification in which the outer face 44 of the lens is plain, and the inner face is provided with a configuration resulting from the combination ofv flutes and prisms. I have indicated one of the vertical prisms built into this form of design by the dotted lines 45. This prism may be resolved into two right triangles having their bases 46 in alignment, and their hypotenuses 48 at an angle to each other as shown. The glass between the hypotenuse and the inner surface 50 of the lens is a conradius of m between the flutes.

ventional flute. I This design has the advan tage that the outer face of the lens may be plain, and, therefore, easily cleaned.

are employe In this .figure I have indicated the built-in prisms by the same reference characters as in Figure 11. Obviously the construction shown in Figures 11 and 12 may be truncated as in the case of Figures 81and 10, if it is desired'to project some light forwardly.

I have also modified the design of lens shown in Figure 4 in'the following manner with successful results. Thusinstead of employing 70 prisms I havemade use of 90 prisms, and instead of using flutes of 7 radius, I have employed flutes having a I have shown this design in Figure13, and this figure likewise illustrates at 60 the flattening of the ridge between the The purpose of this isto allow the light to bend to the extreme angle, and to facilitate manufacture by reducing the depth" beam is shown deflected as at R upon striking the dotted line extension 62 of the ridge provided on the side toward the light source withv vertical prisms and on the side away from the light source with superimposed vermediate said flutes, each prism and its superimposed flute being substantially symmetrical with respect to a plane normal to the plane of the lens and connecting the apex of the prism with the center of curvature of the flute. 2. The lamp set forth in claim 1 in which With the described de the thickness of the lens is in such ratio to the.

angle of the prisms and radius of curvature of the flutes that the extreme rays of the bands passing through any one prismemerge from the corresponding flute at points closely adjacent its lateral extremities and substantially no rays pass through the vertical flats. I

' In testimony whereof I afi'ix my signature.

JOHN L. KOUBEK.

105 tical concave flutes with vertical flats inter- V 

